1. Field of the Invention
The present invention relates to a liquid developer used in image forming devices such as electrophotographic or electrostatic recording copiers, facsimile devices, printers, printing machines, printed wiring board fabricating devices, photomask fabricating devices, and the like, and to a method for manufacturing the liquid developer.
2. Description of the Related Art
Conventional electrophotographic methods generally utilize a photoconductive insulator, as disclosed in U.S. Pat. No. 2,297,691. In such a method, an electrostatic latent image is formed, by irradiating light, on a photoconductive insulator (an electrostatic latent image carrier) which has been charged by a corona or rollers or the like. An image is obtained by developing the electrostatic latent image by electrostatically adhering thereto resin particles which are colored by a pigment or dye (such resin particles are called a toner). After the obtained image is transferred onto paper or a film, it is fused (fixed) by heat, pressure, light, or the like such that a visible image is obtained.
Electrophotographic methods can broadly be classified into dry developing methods and wet developing methods (liquid developing methods). In a dry developing method, toner particles alone are used as the developer, or a mixture of toner and magnetic particles called a carrier is used as the developer. In either case, the developer is used in the form of a powder. The wet developing method utilizes a liquid developer in which toner is dispersed within a liquid which is a carrier.
In order to more faithfully reproduce the electrostatic latent image formed on the photoconductive insulator and to output a more detailed image, it is preferable for the particle diameter of the toner particles to be smaller. However, with the dry developing method, if the particle diameter is small, the interior of the device becomes dirty, handling of the developer is difficult, and the developer is harmful in that it is easy for persons to inhale such small-sized toner particles. Accordingly, in a dry developing method, use of a toner having a particle diameter of about 5 xcexcm or less is unrealistic. On the other hand, in a wet developing method, the toner particles exist within a liquid. Thus, even if toner particles of a particle diameter of about 5 xcexcm or less are used, the aforementioned problems do not arise, and there is the advantage that highly-detailed images can be obtained.
Generally, in a liquid developer used for electrophotography, toner particles, whose main components are a binder resin and a colorant such as carbon black, an organic pigment, a dye or the like, are dispersed in a carrier liquid, whose main component is a substance having good insulating performance and a low dielectric constant such as a petroleum-based aliphatic hydrocarbon or silicone oil. In addition, a charge adjusting agent for imparting an appropriate charge to the toner particles is added into the carrier liquid, and additives for improving the dispersion stability of the toner particles are added into the carrier liquid. Initially, good printing characteristics can be obtained by using a liquid developer prepared from these components. However, there is the problem that, with regard to re-dispersability, the storage environment, deterioration in the printing characteristics accompanying a rise in temperature within the printing device, and the like, sufficient effects are not obtained.
An object of the present invention is to provide a liquid developer which has excellent storage stability and which can enable stable formation of high-quality images over a long period of time, and to provide an effective method for manufacturing the liquid developer, as well as an image forming device and image forming method.
A liquid developer of the present invention comprises: an insulating carrier liquid; toner particles containing a colorant and a binder resin, and insoluble in the insulating carrier liquid; and at least one selected from alkoxy-modified silicone, and silane coupling agents having at least one functional group selected from amino groups, methacryloxy groups, epoxy groups, isocyanate groups, mercapto groups, and vinyl groups.
A method for manufacturing a liquid developer of the present invention comprises the step for compounding: an insulating carrier liquid; toner particles containing a colorant and a binder resin, and insoluble in the insulating carrier liquid; and at least one selected from alkoxy-modified silicone, and silane coupling agents having at least one functional group selected from amino groups, methacryloxy groups, epoxy groups, isocyanate groups, mercapto groups, and vinyl groups.
An image forming method for the present invention comprises: a step for forming an electrostatic latent image on an electrostatic latent image carrier; a step for developing the electrostatic latent image with the liquid developer of the present invention, and forming a visible image; and a step for transferring the visible image onto a transfer material.
An image forming device of the present invention comprises: an electrostatic latent image carrier; means for forming an electrostatic latent image on the electrostatic latent image carrier; means for developing the electrostatic latent image, forming a visible image, and which accommodates the liquid developer of the present invention; and means for transferring the visible image onto a transfer material.